Summary: I upgraded my Intel Core 2 Duo E6400 and I didn't expect to see a big difference but I was amazed I had reviewed the specs so at best I was expected 6% faster. The only problem I was having was my page downloads from the internet I would open then and at times it seemed like forever before they would open. My DVD burn speeds increased dramatically. So I was surprised at the difference in the CPU Usage dropping so much. I would highly recommend this CPU.
Summary: Solid CPU, this is apparently the fastest/best CPU an Optiplex 745 SFF will support. If you have a desktop form factor you can go higher than 65W TDP (and so quad core is an option), but you need to stick with the 6xxx series with a bus speed of 1066 or lower. Also Wolfdale CPUs are NOT compatible with that chipset. I made the mistake of ordering an E6850 and it would NOT boot. The seller I bought from was helpful and let me return it. I then ordered this CPU from them.
Summary: The programs that were taking longer to load are now loading much quicker along with it not lagging as much when the CPU usage is high. So, I highly recommend that anyone with a PC that has a Core 2 Duo processor of lesser GHz to upgrade to this one.
cheap upgrade for relative old computer, giving it new life & performance
18 February 2015
Summary: Upgrading CPU to this one had allowed me to use 64-bit virtualization on my relatively old HP Pavilion a6220.cs. Corresponding the Wintel politics the MS Windows 8.1 Hyper-V virtualization, of course, does not support this (7-years old very outdated:) CPU to serve virtual machine. Everyone knows it, just MS-wintel not (no averse to, disappointment only), therefore i successfully use 3-rd party software VMWARE and/or Virtualbox.